Fjardrárgljúfur canyon- Turn on road 206 (this is a gravel road, it becomes an F-road later own so don't worry) from the ring road and continue for about 2 km until you reach the parking lot of the canyon. There, you can walk along a path and explore the canyon from the top. However, you can also go down the canyon from the start and walk along the river stream. If you want to walk the whole canyon from the bottom, I would then suggest rain boots.

Skaftafell Park- Svartifoss waterfall

Camp in Fjallsárlón Glacier Lagoon- 10km west of Jökulsárlón, from Road 1, a dirt road towards inland with a small signs leads to the glacier which you can see from far away (1.5 km North of Ring road)